North Solent Wader and Wildfowl High Water & Terrestrial Habitat
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North Solent Wader and Wildfowl High Water & Terrestrial Habitat Use: Workshop Outcomes March 2009 North Solent Wader and Wildfowl High Water & Terrestrial Habitat Use: Workshop Outcomes Contents North Solent Wader and Wildfowl High Water & Terrestrial Habitat Use: Workshop Outcomes..................................................................................................................................2 Introduction .............................................................................................................................2 Policy unit assessments......................................................................................................5 Habitat use by waders............................................................................................................5 Selection of roost sites and patterns of use......................................................................5 Roost behaviour in the western Solent ........................................................................6 Roosts behaviour within Southampton Water ...........................................................7 Roost behaviour in Portsmouth Harbour....................................................................7 Roost behaviour in Langstone Harbour ......................................................................8 Roost behaviour in Chichester Harbour......................................................................8 Roost behaviour in Pagham Harbour ..........................................................................8 Terrestrial feeding sites ......................................................................................................9 Habitat use by Dark bellied brent goose and other wildfowl ........................................10 Potential for roost and feeding site recreation..................................................................10 Summary and conclusions...................................................................................................11 Summary of wader roosts within the North Solent SMP................................................13 Introduction Planning for the future conservation of the Solent’s migrant waterfowl populations in the face of rising sea levels requires careful consideration and assessment of different coast defence scenarios. The North Solent Shoreline Management Plan (SMP) provides a strategic document in which to start this process. As sea levels rise some sections of the coast will become increasingly threatened by tidal inundation or potentially greater levels of fluvial flooding. In addition, rising sea level will result in the loss of intertidal habitat in front of coast defences due to coastal squeeze. The SMP will consider options for future management of coast defence structures taking account of these changes. In places, defences may be abandoned (no active intervention), in others, there will be a need to maintain the existing line of defences. Jonathan Cox Associates Ltd 2 Some coast defences many also be deliberately retreated to an inland line. These options will need to be considered within different time scales so that some sections of coast defence may be retained on their existing line for the next 20 years but will be retreated or abandoned in the following 20 years. The SMP has divided the consideration of the future life of coast defences into four time periods or epochs; 0‐ 19 years, 20‐49 years, 50‐100 years and 100 years+. In proposing options for the future of coast defences, the effects of these for the birds that use these different sections of coast need to be assessed. It is generally understood that intertidal mud, sand and mixed sediment flats all play a vital role in providing feeding habitat for many birds, particularly so at low water. However, in addition to intertidal feeding habitat, the migrant bird populations of the Solent require a range of additional habitats to be able to survive through the winter. At high water, wading birds need sites on which to roost whilst the intertidal flats are under water. These are termed high water wader roosts. Some waders also feed on terrestrial habitats inland of the coast, especially wet grassland and marshes. Although wildfowl do not form roosts in the same way as waders, many of the wintering wildfowl in the Solent move between intertidal and terrestrial habitats often on a daily cycle and utilise freshwater wetlands, wet and flooded grasslands and also drier grasslands and even young arable crops. The location of these different habitats and their use by the wintering waterfowl populations of the Solent is not well understood, particularly as the pattern of use can vary from year to year due to changing farming practices and weather conditions. Some of the sites used are included within protected areas such as SSSI, SPA or Ramsar sites. However, many have not statutory protection yet play a significant role in the maintenance of the Solent’s wintering and passage waterfowl populations. A workshop was held on Friday 6th March 2009 to collate the views of local experts on the use of sites around the north Solent shore by wading birds and wildfowl both as roost sites at high water and as terrestrial feeding habitat. The workshop was split into two halves with the morning session considering sites in the western Solent and the afternoon the sites in the eastern Solent. The workshop was attended by the following:‐ Colin Allen (Hythe Marshes WeBS counter) Ian Watts (Itchen Estuary WeBS counter) Peter Potts (HCC Royal Victoria CP and wider Solent) Ivan Lang (Pagham Harbour) Peter Durnell (HCC Lymington and Keyhaven) Ed Rowsell (Chichester Harbour Conservancy) Katherine Rowborough (Langstone Harbour Board) Jonathan Cox Associates Ltd 3 Chris Cockburn (RSPB Langstone Harbour) Claire Lambert Samantha Cope Andrew Colenutt Tim Sykes Jonathan Cox Comprehensive briefing notes were also received from Mark Larter, NE North Solent NNR. Attendants at the workshop were invited to give their views on the use of each section of the Solent’s coast by waders and wildfowl. This information was recorded on maps and as notes. This brief report reflects the discussion that took place at the workshop. It initially provides a review of the use by waterfowl of high water roost and terrestrial feeding sites. This is followed by a review of the use of high water roost and terrestrial feeding habitats within each sector of the north Solent shore from Hurst Spit in the west to Pagham Harbour in the east. Information gathered in the workshop has been collated onto maps. These combine information made available by the Hampshire and Isle of Wight Wildlife Trust with that provided from the workshop attendants. Two sets of maps have been produced. The first of these provides information on wader use and the second on use of terrestrial habitats by dark bellied brent geese and other wildfowl. The Wildlife Trust’s maps provided an assessment of wader roost1 and brent goose feeding sites2 based upon observer information including numbers of birds present and frequency of occupation. Sites were graded as follows:‐ Red Major importance Orange High importance Green Low to moderate importance Blue No recorded use The workshop attendants were asked to grade sites using this same grading system. However, no data was used to distinguish between importance levels. Grading of the sites was therefore based upon the contributors’ experience of sites over a number of years. 1 NS_High_Tide_Roost_Wader.pdf 2 NS_High_Tide_Roost_Brent.pdf Jonathan Cox Associates Ltd 4 Due to the range of experience of those present at the Workshops, some parts of the Solent shore were better understood than others. For example, the shoreline between Lymington and Beaulieu was not well known by any of the contributors. This is reflected in the large number of sites with ‘no recorded use’ on this section of shore. Policy unit assessments Using the information provided from the Workshops an assessment was made of potential coast defence policy options for each section of coast3. This considered a limited number of standardised options for each coast section; Hold the Line, Retreat the Line or No Active Intervention. Many of the important waterfowl roost and feeding sites identified from the Workshop are not protected by coast defences and hence were not affected by coast defence options. Offsetting measures for the loss of these sites to sea level rise may be required in the context of site management plans. It should be possible to provide compensation or mitigation for the loss of the smaller and less complex waterfowl roost and feeding sites that are protected by coast defences. Suggested compensation strategies have been identified in the assessment matrix for these. In most instances, compensation/mitigation would be required across all three time epochs of the Shoreline Management Plan (SMP). Maintaining the line of coast defences in front of these sites is a potential management strategy, however, this approach would be counter to objective of maintaining naturally self sustaining coastlines and it is likely to have other adverse effects on habitats of international importance through coastal squeeze. For three large and complex sites, it was considered that compensation could not be provided and that coast defences should be maintained for the first epoch of the SMP period to maintain the function of the SPA concerned. A final assessment for the need to maintain defences in front of individual waterfowl roosting